I dropped an email to Lind Electonics, http://www.lindelectronics.com/ , to see if they had some thing that could filter and regulate at 13.2v. They make a good DC DC power supply that can take a range of voltage and keep it at what its designed for. I always use them on my laptops and the ones I help other people set up for their own use. I'll post when they answer.

WarrenMN